Method of manufacturing bobbins

ABSTRACT

THE BOBBIN DISCLOSED HEREIN IS AN ARTICLE ON WHICH CONDUCTOR WIRE IS WOUND TO PROVIDE AN INDUCTOR, SUCH AS A TRANSFORMER. THE BOBBIN INCLUDES A GENERALLY TUBULAR SECTION EQUIPPED WITH END FLANGES AND THE TUBULAR SECTION IS CONSTRUCTED OF INNER LAYERS OF PAPER AND AN OUTER LAYER OF FILM. INTERPOSED BETWEEN THE OUTERMOST PAPER LAYER AND THE FILM LAYER IS A LAYER PREVIOUSLY MADE INTO A LAMINATE-HAVING A PAPER FACE AND A FILM FACE WITH THE PAPER FACE ABUTTING THE OUTERMOST PAPER LAYER.

19H mus mu.

METHOD OF MANUFACTURING BOBBINS Filed Nov. 6, 1968 PR E-LAMI NATE FIGG ROBERT C. ELLIS GEORGE A, YOUNG ATT'YS United States Patent 3,595,723 METHOD OF MANUFACTURING BOBBINS Robert C. Ellis, Kenilworth, 111., and George A. Young, Bay Village, Ohio, assignors to Precision Paper Tube Company, Wheeling, Ill.

Filed Nov. 6, 1968, Ser. No. 773,730 Int. Cl. B31c; B65h 81/00 US. Cl. 156-190 3 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND AND SUMMARY OF THE INVENTION The instant invention is an improvement on two prior co-owned patent Nos. 2,644,651 and 2,736,956. The earlier patents deal with a bobbin having a tubular portion made up of paper and cellulose acetate. Such bobbins were disadvantageous at times due to separation of layers, particularly the paper and acetate layers. Once this occurred, a gap was developed which created a potential current leakage path. Also, where the bobbin was of rectangular cross section so as to receive metal laminations (as for constructing a transformer) the drooping character of the tubular portion because of the layer separation protruded into the path of metal lamination insertion, often resulting in cuts. This occurred after the bobbin had been wound with conductor wire and required expensive labor in order to salvage the costly copper wire.

According to the instant invention, a novel laminate previously formed of paper and film is interposed as an intermediate layer, being bonded to both the paper and film or plastic layers heretofore known and which results in a sturdy, integral tubular portion for the inventive bobbin-thereby avoiding the drawbacks of previously employed structures.

It is an object of this invention to provide a novel bobbin and the method of manufacture as indicated above. Other objects and advantages of the invention may be seen in the details of construction and manufacture as set forth in the ensuing specification.

DETAILED DESCRIPTION The invention is described in conjunction with an illustrative embodiment in the accompanying drawing, in which- FIG. 1 is a perspective view of the inventive bobbin;

FIG. 2 is a cross sectional view of the bobbin of FIG. 1 as Would be seen along the sight line 2-2 applied thereto;

FIG. 3 is a fragmentary, enlarged sectional view of the portion encircled in FIG. 2;

FIGS. 4 and 5 are schematic elevational views of the inventive bobbin in an intermediate stage of manufacture; and

FIG. 6 is a sectional view of the bobbin of FIG. 1 in its completed form and shown in the process of being wound with conductor wire.

In the illustration given and with reference to FIG. 1, the numeral 10 generally designates a bobbin constructed in accordance with the teachings of this invention. The

bobbin is seen to include a central tubular portion 11 and end flanges 12 and 13. As indicated previously, the general construction employed here can be seen in US. Pat. No. 2,644,651. When a bobbin reaches the condition seen in FIG. 1, it is adapted to be wound with conductor wire as at 14 as seen in FIG. 6. Prior to that stage, the tubular section 11 is equipped with the end flanges 12 and 13this operation being indicated schematically in FIGS. 4 and 5. In FIG. 4, the tubular section 11 is seen mounted on an arbor 15 with the flanges 12 and 13 being ensleeved on the tubular portion 11 intermediate the ends thereof. The application of a solvent is indicated schematically in FIG. 4 and after this is done to soften the exterior of the tubular portion 11, the flanges 12 and 13 are moved outwardly by suitable plow means (not shown) from the intermediate positions designated 12 and 13 in FIG. 5. One procedure for achieving this is disclosed in co-owned US. Pat. No. 2,950,527. After the end flanges are. positioned as seen in FIG. 5, the eX- treme ends of the tubular member 11 may be swaged as at 16 in FIG. 6.

The instant invention has to do with the tubular member 11 and the method of making the same whereby a distinctly stronger and superior-operating bobbin is ultimately achieved.

In the process of making the tubular member 11, a series of strips are spirally wound on an arbor (not shown, but similar to that designated 15) to provide a layered tube of generally rectangular cross section.

For example, a first strip 17 is wound on the arbor with adjacent convolutions abutting each other as at 18. Thereafter a second paper strip is spirally wound on the arbor and overlying the strip 17 to provide the layer designated 19 with adjacent convolutions of the strip 19 abutting each other as at 20. Thus, the edges of adjacent layers are not in line but are overlapping. Although only two paper layers are shown herein, it will pe appreciated that in many instances a larger number, i.e., 4 or 5 layers may be used. Advantageously, each layer has a thickness of the order of about 0.05 inch to about 0.015 inch.

After the outermost paper layer has been wound on the arbor and adhesively secured to the previously wound paper strip, a laminate generally designated 21 is overwound, also in spiral fashion. The strip 21 is a prelaminate of paper and film or plastic consisting of a paper lamina 22 and a plastic lamina 23 which, as indicated previously, may advantageously be of cellulose acetate. In the illustration given, the paper face or lamina of the layer 21 is positioned in confronting relation with the previous layer 19. The two are adhesively bonded by an adhesive such as Fullers No. 2708 which is not affected by acetone. As indicated in FIG. 3, the adjacent convolutions of the layer 21 abut each other as at 24-again offset from the adjacent convolutions.

Finally, the outermost layer 25 is spirally wound and this is advantageously constructed of the same plastic or film material as the plastic lamina 23. In each case, the lamina 23 and the layer 25 may be constructed of cellulose acetate having a thickness of the order of about 0.001 inch to about 0.004 inch. The lamina 22 advantageously has a thickness of the order of about 0.002 inch to about 0.007 inch. The layer 25 is united to the lamina 23 through the use of a solvent which incorporates acetone and methylisobutyl ketone and may take the form of the solvent disclosed in Pat. No. 2,644,651.

It will be appreciated that the tabular portion 11 may have various cross sections, i.e., round, square, etc., depending upon the electrical application involved. In like fashion other films or plastics may be employed such as polyethylene, polyvinyl chloride, heat softenable adhesives and other adhesive films which can be made adherent each 3 to itself and to paper-to form the above described laminate 21.

We claim:

1. In a process of manufacturing a bobbin or the like, the steps of sequentially spirally winding strips of material to provide a multi-layered tube, the strip edges in one layer overlying an intermediate portion of the strip in an adjacent layer, at least the first strip wound being constructed of paper, the next to the last strip being a laminate strip of plastic and paper, said laminate strip having been laminated separate from said step of spirally winding, positioning the said next to the last strip so that the paper side therein is in confronting relation with a previously wound paper strip, and adhesively bonding adjacent strips together.

2. The process of claim 1 in which each paper strip has a thickness of the order of about 0.005 inch to about 0.015 inch, said laminate having the paper portion of a thickness of the order of about 0.002 inch to about 0.007 inch and the plastic portion of a thickness of the order of about 0.001 inch to about 0.004 inch, the said plastic strip having a thickness of the order of about 0.001 inch to about 0.004 inch.

3. In a process of inductor manufacture, the steps of spirally winding at least two paper strips on a generally 2 rectangular arbor while adhesively securing adjacent strips together and with adjacent strips being in edge overlapping relation to each other, spirally winding on said arbor a laminate strip of film and paper and adhesively securing the paper face of said laminate 10 Winding a wire conductor on the tubular part between the end flanges thereof.

References Cited UNITED STATES PATENTS 2,644,631 7/1953 Stahl 2421l8.7 2,755,821 7/1956. Stahl 242ll8.32 2,756,003 7/1956 Stahl 242-11832 2,945,638 7/1960 Crawford et al. 4-- 242118.32 3,054,428 9/1962 Crawford 13814l 3,323,751 6/1967 Cunningham et a1. 242118.32 3,350,030 10/1967 Green 242-118.32 3,362,655 l/1968 Roediger 242118.32

5 CARL D. QUARFORTH, Primary Examiner G. G. SOLYST, Assistant Examiner US. Cl. X.R. 

